Means for separating oil from the refrigerant in refrigerating systems



July 8 1924.

T. SHIPLEY IN REFRIGERATING SYSTEMS Filed Jan. 4, 192

MEANS FOR SEPARATING OIL FROM THE REFRIGERANT Patented July 8, 1924.

UNITED STATES PATENT OFFICE.

THOMAS SHTPLEY, OF YORK, PENNSYLVANIA.

IEANS FOR SEPARATING OIL FROM T HE REFRIGERANT IN REFRIGERATING SYSTEMS.

Application filed January 4, 1924. Serial No. 684,348.

To all whom it may concern:

Be it known that I, THOMAS SHIRLEY, a citizen of the United States, residing at York, in the county of York and State of Pennsylvania, ha've invented certain new and useful Improvements in Meansv for Separating Oil from the Refrigerant in Refrigerating Systems, of which the following is a specification.

Th s invention relates to refrigeration, and particularly to means for removing oil and the like from ammonia and other refrigerant gas.

In a prior application, Serial No. 666,196, filed October 2, 1923, I describe and claim a method of and means for separating oil from the refrigerant in refrigerating systems, and the present application relates to a modified form of apparatus for carrying out the method aforesaid.

The apparatus forming the subject of the present application is particularly adapted for use with compressors of the two-stage type.

The difficulties arising from the congelation of lubricating oil in the expansion valve and in the cooling coils of refrigerating systems are well known. The'broad principle involved in the prior application, above identified, involved the removal of the oil by the interposition of a strainer or filter in the path of the liquefied refrigerant as the latter leaves the condenser. Such a filter necessarily ofiers resistance to the' flow of the liquefied refrigerant and it therefore becomes necessary to provide for a pressure drop through the filter. In the prior application this result is secured by the use of' a supplemental cooler interposed in the liq-.

uid refrigerant line on the discharge side of the filter, operating to produce a temperature drop corresponding to the desiredpressure drop through the filter, and thus serving to prevent evaporation of any portion of she liquid refrigerant despite the pressure rop.

The present invention relates to 'a special form of apparatus in which'this pressure drop is secured by connecting the discharge side of the filter to the intermediate receiver forming a part of a two-stage compression system. In such a system the intermediate pressure is determined by the number of compressions and the ratio between the high and low pressure cylinders, but since this pressure is lower than high pressure receiver pressure, part of the liquid refrigerant in the intermediate receiver will vaporize and by such vaporization" cool the remainder. Thus, as in the prior application, we have two stages of cooling of the refrigerant, the first in the condenser and the second in the intermediate receiver, and, between these cooling stages the refrigerant is maintained in liquid form and filtered under an effective pressure corresponding to the temperature difi'erence.

The accompanying drawing illustrates in diagram a preferred embodiment of the invention as applied to one well known type of refrigerating system.

The parts can best be identified by tracing out the path of the refrigerant in the system.

Liquefied refrigerant passes from the intermediate receiver 1 through the cold liquid line 2 to the expansion valve 3, through which it expands into the cooling coil 4. The coil 4 is submerged in the usual brine tank 5 and acts to chill the brine.

The evaporated refrigerant flows by way of pipe 6 to a trap 7, which separates and collects any entrained liquid refrigerant, and returns it by way of pipe 8 to the coil 4. The remaining gaseous refrigerant thus freed of entrained liquid passes by way of the low pressure suction line 9 to the low pressure compressor 10, where it is compressed. It

passes thence by the pipe 11 to the intermediate pressure gas cooler 12 Where. it is.

culated in the coil 13.

From the gas cooler 12 the gas passes by the high pressure suction line 14 to the high pressure compressor 16 where ,1t 1s compressed further. A branch connection 15 from the top of intermediate receiver 1 cooled by water or'other cooling agency cirleads to the high pressure suction line. Thisensures the existence of high pressure sue-- tion pressure in the intermediate receiver and causes vaporization of a part of the liqv uid refrigerant in the receiver and the con- From high pressure cylinder 16 the refrigerant flows by the high pressure dlscharge' line 17 to the condenser 18,'where it is cooled and liquefied.

.sequent cooling of the liquid refrigerant .therein to the corresponding temperature.

All the parts so far described are familiar I to those skilled in the art and illustrate one known type of installation usin a two-stage compressor. The details are su ject to considerable variation. The present invention involves the path of the refrigerant from the condenser 18 to the intermediate receiver 1.

From the bottom of condenser 18 liquid refrigerant flows by gravity to the high pressure liquid receiver 19. Thence it flows to a gravity oil separating trap 20, of usual form, provided wlth gage glasses 21 and a valved oil-draw-ofi connection 22. From the top of trap 20 the refrigerant flows through one or the other of two filter heads 23 which are provided each with valves 24 and 25, to permit them to be connected in the refrigerant line or cut out in alternation so that one may be cleaned while the other is in use. A pxump-out connection for the filter heads is s own at 26.

From the filter 23therefrigerant flows through pipe 27 and reducing valve 28 to the intermediate receiver 1. The low pressure cylinder operates to maintain the desired low pressure in the refrigeratin coils 4 and delivers the refrigerant at a higher pressure to the intermediate pressure gas cooler where it is partially cooled. The high pressure cylinder 16 com resses the refrigerant flowin from the intermediate pressure gas coo er and delivers it to the condenser 18. It also withdraws gaseous refrigerant through the pipe 15 from the receiver 1.

The refrigerant is cooled and liquefied by the condenser 18 under high pressure discharge pressure, and is accumulated in liquid form, under that pressure, in the high pressure receiver 19 and oil separating trap 20. The filter and the reducing valve 28 operate conjointly to maintain the desired differential pressure between the high pressure receiver and the intermediate receiver 1. A part of this differential pressure does the work of forcing the liquefied refrigerant through the filter in the head 23. The reason for using the reducing valve is to adjust the rate of flow to the intermediate receiver.

The invention is not restricted to any articular type of filter head 23, as any ter capable of operating under the available effective pressure, and of easing a liquid refrigerant such as anhy rous ammonia, while preventing the passa e of lubricating oil may be used. The hig and low pressure compressors may be separate compressors, each driven independently of the other at the proper rate, or the two may be connected as in the conventional type of twostage compressors.

Theinvention has peculiar advantages because the oil is removed in a cool part of the system where the oil is in a 1i uid condition. This permits a substantia y complete elimination of the oil and virtuall precludes the accumulation of congealed oi in the ex pansion valve and in the cooling coils.

What is claimed is:

1. The combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor stages and an intermediate receiver subject to'the suction pressure of the high pressure stage, and connected to receive liquefied refrigerant from the condenser and to feed it to the evaporator, of anoil removing filter interposed in the refrigerant line between the condenser and the intermediate receiver.

2. The combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor stages and an intermediate receiver subject to the suction pressure of the high pressure stage, and connected to receive llquefied refrigerant from the condenser and to feed it to the evaporator, of an oil separatin trap and an oil removing filter interpose in the refrigerant line in the order stated between the condenser and the intermediate receiver.

3. The combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor sta es and an intermediate receiver subject to t e suction pressure of the high pressure stage, and connected to receive liquefied refrigerant from the condenser and to feed it to the evaporator, of an oil removing filter and a pressure reducing valve interposed in the refrigerant line between the condenser and the intermediate receiver.

4. The combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor stages and an intermediate receiver subject to the suction pressure of the high pressure stage, and connected to receive li .uefied refrigerant from the condenser an to feed it to the evaporator, of an oil separating trap, an oil removing filter and a pressure reducing valve interposed in the order stated in the refrigerant line between the condenser and the intermediate receiver. 7

5.- In a refrigerating system, the combination of a receiver, an exaporator fed by the receiver, two compressor stages connected in series to withdraw gaseous refrigerant from the evaporator, a condenser connected to receive compressed refrigerant from the second compressor stage, a connection between said receiver and a point in the refrigerant line between the two stages of the compressor, whereby the receiver is maintained atinterstage ressure, a connection for feeding liquefie refrigerant from the condenser to said receiver and an oil removing filter inte osed in the last named connection.

6. e combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor stages and an intermediate receiver connected to the refrigerant line between stages. and arranged to" feed liquefied refrigerant' to the evaporator, of a pressure reducing connection for conveying ant from the condenser to the receiver and including an oil removing filter.

7. The combination with a refrigerating system of the compressor condenser evaporator circuit type, including two compressor stages, a high pressure receiver arran ed to receive liquefied refrigerant at con enser lquefied refrigerpressure and an intermediate receiver maintamed at a lower'pressure and temperature than the high pressure receiver, by means of celver and the intermediate receiver, said connection including an oil removing filter. In testimony whereof I have signed my name to thls specification.

THOMAS SHIPL-EY. 

